From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wols Lists Subject: Re: 4.11.2: reshape raid5 -> raid6 atop bcache deadlocks at start on md_attr_store / raid5_make_request Date: Tue, 23 May 2017 15:16:08 +0100 Message-ID: <59244428.4050001@youngman.org.uk> References: <87lgppz221.fsf@esperi.org.uk> <87a865jf9a.fsf@notabene.neil.brown.name> <87fufwy3lr.fsf@esperi.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87fufwy3lr.fsf@esperi.org.uk> Sender: linux-raid-owner@vger.kernel.org To: Nix , NeilBrown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 22/05/17 22:38, Nix wrote: > Everything else hangs the same way, too. This was surprising enough that > I double-checked to be sure the patch was applied: it was. I suspect the > deadlock is somewhat different than you supposed... (and quite possibly > not a race at all, or I wouldn't be hitting it so consistently, every > time. I mean, I only need to miss it *once* and I'll have reshaped... :) ) > > It seems I can reproduce this on demand, so if you want to throw a patch > with piles of extra printks my way, feel free. Could this be the long-standing bug that hangs raid5 and raid6 reshapes? I don't remember it being found and fixed. iirc (it's too long ago) it hit people adding a drive to a raid5 (occasionally a raid6), and was fairly easy to get round. Again it's too long ago but stopping and starting the reshape fixed it usually iirc. Cheers, Wol